The present invention concerns a method for perforating foil, in particular synthetic foil, such as any so-called stretch foils, high-density foils, foils in polyethylene, in polypropylene, etc.
More in particular, the present invention concerns a method for providing perforations with relatively large dimensions in foils in an efficient and rational manner, for example, in the case of circular perforations, of the size of 6 to 60 mm.
The present invention also concerns a device using the above-mentioned method, as well as foil obtained by means of such method, device respectively.
Until now, no methods, devices respectively, are known for providing relatively large perforations in foil material.
Methods and/or devices are already known, however, for providing relatively small perforations in foil material, in other words, perforations having a maximum diameter of 6 mm.
A first known device for providing such small perforations in foil material consists of a mould through which the foil is lead through, and whereby the lead-through of said foil through the mould happens in steps, in other words whereby the foil must be stopped each time a row of perforations is provided.
This known device can in no way be efficiently used for providing perforations of relatively large dimensions in foil material, since, from the nature of things, it works very slowly on the one hand, and since the discharge of the punched-out discs is difficult, if not impossible, especially when the foil material is very thin, since the discs very often stick to the foil material in this case, either because it has not been entirely cut away, either due to the electrostatic charge in the material, as a result of which the loosened discs remain stuck.
In a second known device, use is made of bullets for providing perforations which are driven with force through a hollow pipe upon which the foil to be perforated is placed.
This second known device has all the above-mentioned disadvantages of the first known device.
In a third known device for providing perforations with a small diameter in foil material, use is made of nails to prick through the foil material.
Besides the above-mentioned disadvantages of the two first known devices, this third device is also disadvantageous in than the perforations are only formed by pricking through the material, such that no real openings are formed.
It is clear that the material obtained by providing small perforations with any of the above-mentioned known devices can only be used in a restricted manner, for example only as agricultural foil, in other words, foil for covering large surfaces.